Where are the rear motor mounts on a mercruiser 120?

[Mike Lukacevic]

Can’t get rid of the knock on this n”ew to me boat” and figure I should pull it and replace the bearings. I’m wondering how long the Total job should take got all the tools and access to a hoist. Any tips to avoid a slow down. Think the PO gave me a bit of a bend over. Least the parts are cheap. Girding my loins to get this job done.

 

[Scott06]

Can’t get rid of the knock on this n”ew to me boat” and figure I should pull it and replace the bearings. I’m wondering how long the Total job should take got all the tools and access to a hoist. Any tips to avoid a slow down. Think the PO gave me a bit of a bend over. Least the parts are cheap. Girding my loins to get this job done.

Rear mounts are on the flywheel cover two larger bolts hold it to the transom plate. Be careful the older ones use a spring and washer under thr mount , dont loose them when you take it out.
measure the hoist you are using with a boat on a trailer you have to get the engine way up t9 clear the gunnel

 

[Bondo]

Ayuh,.... 'n pull the drive off 1st,....

 

[Mike Lukacevic]

Rear mounts are on the flywheel cover two larger bolts hold it to the transom plate. Be careful the older ones use a spring and washer under thr mount , dont loose them when you take it out.
measure the hoist you are using with a boat on a trailer you have to get the engine way up t9 clear the gunnel

I’ve heard about liftin the younger of the trailer and if that doesn’t work remove the wheels. Sound copacetic

 

[Mike Lukacevic]

Ayuh,.... 'n pull the drive off 1st,....

I’m gonna store the drive in yer living room if ya don’t mind, matey. Shouldn’t be more than a month or so.

 

[Mike Lukacevic]

Rear mounts are on the flywheel cover two larger bolts hold it to the transom plate. Be careful the older ones use a spring and washer under thr mount , dont loose them when you take it out.
measure the hoist you are using with a boat on a trailer you have to get the engine way up t9 clear the gunnel

Aye. The mounts on the back. There be darkness and parrots feathers there. Hope I can get a spanner there and not rip up the soft skin on my forearms fore she finds herself loosened

 

[Mike Lukacevic]

Come on. So how long, with a decent mechanic should this job take? I’ve already diagnosed every electrical, ignition and I’ve got this thing looking like it’s straight out a the Brady Bunch. I’m trying to keep it light though I’m taking the engine out and changing some bearings.

Brass tacks. What kinda time consuming issues will I run into? Pulling bearings off caps? Stuck cap bolts? Emory cloth to crank?

Well there be any problem just dumping the engine over with all the parts on including the carb?
I m looking for the wizard of doing this. Where’s the wizard? Where are you? Step up for salvation.

 

[Scott Danforth]

Come on. So how long, with a decent mechanic should this job take? I’ve already diagnosed every electrical, ignition and I’ve got this thing looking like it’s straight out a the Brady Bunch. I’m trying to keep it light though I’m taking the engine out and changing some bearings.

Brass tacks. What kinda time consuming issues will I run into? Pulling bearings off caps? Stuck cap bolts? Emory cloth to crank?

Well there be any problem just dumping the engine over with all the parts on including the carb?
I m looking for the wizard of doing this. Where’s the wizard? Where are you? Step up for salvation.

Get the factory service manual

 

[Bondo]

Come on. So how long, with a decent mechanic should this job take? I’ve already diagnosed every electrical, ignition and I’ve got this thing looking like it’s straight out a the Brady Bunch. I’m trying to keep it light though I’m taking the engine out and changing some bearings.

Brass tacks. What kinda time consuming issues will I run into? Pulling bearings off caps? Stuck cap bolts? Emory cloth to crank?

Well there be any problem just dumping the engine over with all the parts on including the carb?
I m looking for the wizard of doing this. Where’s the wizard? Where are you? Step up for salvation.

Ayuh,..... In my shop, I could have the motor bolted to a stand on the floor in under an hour,.....

 

[Scott06]

Aye. The mounts on the back. There be darkness and parrots feathers there. Hope I can get a spanner there and not rip up the soft skin on my forearms fore she finds herself loosened

Use two long extensions on a 1/2" drive breaker bar.. You can get the engine out quick but if you have a rod or main bearing knock just replacing the bearing isn't going to do you any good with out having it remachined. Need to check the journals for size and resize as needed.

Did you rule out any valve train issues or is it a deeper noise than valve train ?

Brass tacks. What kinda time consuming issues will I run into? Pulling bearings off caps? Stuck cap bolts? Emory cloth to crank?

Well there be any problem just dumping the engine over with all the parts on including the carb?
I m looking for the wizard of doing this. Where’s the wizard? Where are you? Step up for salvation.

 

[Mike Lukacevic]

Use two long extensions on a 1/2" drive breaker bar.. You can get the engine out quick but if you have a rod or main bearing knock just replacing the bearing isn't going to do you any good with out having it remachined. Need to check the journals for size and resize as needed.

Did you rule out any valve train issues or is it a deeper noise than valve train ?

Thanks. I figured I’d have to get the extensions out. Maybe my impact. Who knows.
I’ve done a dynamic and a static valve adjustment. Listened all over with a stethoscope, but since this is my first experience with this engine I’ve got nothing to compare it to.
I pulled off the the oil filter and ripped it apart, pressed the oil out in a vice. There’s metal. But not crazy amounts. Still it’s a crappy sight.
Poured in some liqui moly and prayed. not a thing after about 15 minutes.
The oil pressure is spec, which puzzles me. The compression is perfect.
I’ve got parts ordered—-didn’t think about the crank too much—but wondering if I should just slap a used motor into it. I’ll attach a video of this thing running. It’s pretty accurate. Just pissed I bought the thing.

 

[Scott06]

Thanks. I figured I’d have to get the extensions out. Maybe my impact. Who knows.
I’ve done a dynamic and a static valve adjustment. Listened all over with a stethoscope, but since this is my first experience with this engine I’ve got nothing to compare it to.
I pulled off the the oil filter and ripped it apart, pressed the oil out in a vice. There’s metal. But not crazy amounts. Still it’s a crappy sight.
Poured in some liqui moly and prayed. not a thing after about 15 minutes.
The oil pressure is spec, which puzzles me. The compression is perfect.
I’ve got parts ordered—-didn’t think about the crank too much—but wondering if I should just slap a used motor into it. I’ll attach a video of this thing running. It’s pretty accurate. Just pissed I bought the thing.

Doesnt sound like a rod or main knock to me. Might loosen up the belt and run it with out the accessories and water pump turning.

Sounds more top end to me, hard to diagnose from keyboard but I wouldn't be tearing it out just yet.

 

[Mike Lukacevic]

Doesnt sound like a rod or main knock to me. Might loosen up the belt and run it with out the accessories and water pump turning.

Sounds more top end to me, hard to diagnose from keyboard but I wouldn't be tearing it out just yet.

That was one of the things I’ve done.
That’s why it’s puzzling. Also, took the plug wires off to isolate. I’ve got pretty good hearing but I couldn’t really discern any difference. As you can see the compression is great. All four are like that. Maybe I should put the cowl on, turn up the stereo and take it to a lake. It’s nice and shiny anyway.
I really appreciate the time you’ve taken. I’m here in Pittsburgh and none of my buddy’s know a thing about, or are interested in these things, so it’s a bit of an isolated business. It’s nice to share diagnostics with another person.

 

[Scott06]

That was one of the things I’ve done.
That’s why it’s puzzling. Also, took the plug wires off to isolate. I’ve got pretty good hearing but I couldn’t really discern any difference. As you can see the compression is great. All four are like that. Maybe I should put the cowl on, turn up the stereo and take it to a lake. It’s nice and shiny anyway.
I really appreciate the time you’ve taken. I’m here in Pittsburgh and none of my buddy’s know a thing about, or are interested in these things, so it’s a bit of an isolated business. It’s nice to share diagnostics with another person.

Outside of Philly myself

Did u measure the lift on the valves ? Wonder if u have a flat cam lobe. I know y tightened rockers but wonder if you are getting full lift ?
3.0 uses timing gears might have wear and backlash ? Could probably check by taking cap of dist and move crank back and forth see if there is a lag before the rotor moves

 

[Mike Lukacevic]

Outside of Philly myself

Did u measure the lift on the valves ? Wonder if u have a flat cam lobe. I know y tightened rockers but wonder if you are getting full lift ?
3.0 uses timing gears might have wear and backlash ? Could probably check by taking cap of dist and move crank back and forth see if there is a lag before the rotor moves

Hmmm. Interesting.
You’ll have to take a leap here when I tell ya the top end-rockers, springs even the nuts look newer. I’ve considered the gears as well. Sure looked, at first glance, that they’d be easy to pull off then tap back on with some mallet or such. Then I looked at the manual. Hahaha! I’m gonna try what yer saying. It kinda appears that the most noise MIGHT be coming from there. You’d think that it’d be simple. Sure.
Now I need a mate to go out with me. Preferably naive. But good with a paddle and with a good attitude. Thanks.

 

[Scott06]

Hmmm. Interesting.
You’ll have to take a leap here when I tell ya the top end-rockers, springs even the nuts look newer. I’ve considered the gears as well. Sure looked, at first glance, that they’d be easy to pull off then tap back on with some mallet or such. Then I looked at the manual. Hahaha! I’m gonna try what yer saying. It kinda appears that the most noise MIGHT be coming from there. You’d think that it’d be simple. Sure.
Now I need a mate to go out with me. Preferably naive. But good with a paddle and with a good attitude. Thanks.

Not a leap just spit balling.

If you can support the end of the engine you can remove the front mount and pull the cover off, but I am not sure if you can re-isntall with out dropping the oil pan.

 

[Scott Danforth]

This thread has taken longer than it would have taken to pull the drive and motor

 

[nola mike]

Could also check vacuum if you're thinking cam lobe. Exhaust flappers can sound like that. Or exhaust leak.

 

[Mike Lukacevic]

This thread has taken longer than it would have taken to pull the drive and motor

No kidding. But I’m 63 and not in a hurry.

 

[Scott06]

This thread has taken longer than it would have taken to pull the drive and motor

But does it need to come out? Could be wrong but noise doesn't sound like a rod or main bearing.